Feeding the Hungry
(ט) וּבְקֻצְרְכֶם אֶת קְצִיר אַרְצְכֶם לֹא תְכַלֶּה פְּאַת שָׂדְךָ לִקְצֹר וְלֶקֶט קְצִירְךָ לֹא תְלַקֵּט. (י) וְכַרְמְךָ לֹא תְעוֹלֵל וּפֶרֶט כַּרְמְךָ לֹא תְלַקֵּט לֶעָנִי וְלַגֵּר תַּעֲזֹב אֹתָם אֲנִי יְהוָה אֱלֹהֵיכֶם.
(9) And when ye reap the harvest of your land, thou shalt not wholly reap the corner of thy field, neither shalt thou gather the gleaning of thy harvest. (10) And thou shalt not glean thy vineyard, neither shalt thou gather the fallen fruit of thy vineyard; thou shalt leave them for the poor and for the stranger: I am Adonai your God.
This is known as the mitzvah of Pe'ah, leaving the corners of the field unharvested for the poor to take.
(ז) כִּי יִהְיֶה בְךָ אֶבְיוֹן מֵאַחַד אַחֶיךָ בְּאַחַד שְׁעָרֶיךָ בְּאַרְצְךָ אֲשֶׁר יְהוָה אֱלֹהֶיךָ נֹתֵן לָךְ לֹא תְאַמֵּץ אֶת לְבָבְךָ וְלֹא תִקְפֹּץ אֶת יָדְךָ מֵאָחִיךָ הָאֶבְיוֹן. (ח) כִּי פָתֹחַ תִּפְתַּח אֶת יָדְךָ לוֹ וְהַעֲבֵט תַּעֲבִיטֶנּוּ דֵּי מַחְסֹרוֹ אֲשֶׁר יֶחְסַר לוֹ.
(7) If there be among you a needy man, one of thy brethren, within any of thy gates, in thy land which Adonai thy God giveth thee, thou shalt not harden thy heart, nor shut thy hand from thy needy brother; (8) but thou shalt surely open thy hand unto him, and shalt surely lend him sufficient for his need in that which he wanteth.
(ז) הֲלוֹא פָרֹס לָרָעֵב לַחְמֶךָ וַעֲנִיִּים מְרוּדִים תָּבִיא בָיִת כִּי תִרְאֶה עָרֹם וְכִסִּיתוֹ וּמִבְּשָׂרְךָ לֹא תִתְעַלָּם. (ח) אָז יִבָּקַע כַּשַּׁחַר אוֹרֶךָ וַאֲרֻכָתְךָ מְהֵרָה תִצְמָח וְהָלַךְ לְפָנֶיךָ צִדְקֶךָ כְּבוֹד יְהוָה יַאַסְפֶךָ.

(7) Is it not to share your bread with the hungry and to take the wretched poor into your house; when you see the naked to clothe him and not to ignore your own kin? (8) Then shall thy light break forth as the morning, And thy healing shall spring forth speedily; And thy righteousness shall go before thee, The glory of Adonai shall be thy rearward.

(ז) ... ואבד העושר ההוא בענין רע, שהשיב לאותו העני בענין רע ואמר לו: לית את אזיל לעי ונגיס?! חמי שקיין, חמי כרעין, חמי כרסוון, חמי קפרן! אמר לו הקדוש ברוך הוא: לא דייך שלא נתת לו משלך מאומה, אלא במה שנתתי לו את משים בו עין רעה!
...The rich man may say to the poor one: "Why don't you go out and work at a job?! Look at those thighs! Look at those shanks! Look what a great belly (you have)!"
The Holy One will then say to the rich man: Is it not enough for you that you gave him nothing of yours! Must you also cast a mocking eye on what I gave him?!
5. Taanit 21 a
It is related of Nahum of Gamzo (a famous scholar) that he was blind in both eyes, stumped in both hands and crippled in both legs; his entire body was covered in boils...His disciples asked, "Master, since you are so perfectly righteous, why has all this affliction come upon you?" He replied, "My children, I invoked it upon myself.
"Once I was journeying to my father-in-law's house and had with me three heavily laden asses, one with food, one with drink and one with all kinds of delicacies. A poor man appeared on the road and stopped in front of me, saying, "Master, give me food." I replied, "Wait until I unload the ass." I had barely managed to do so when the poor man died (from hunger). I threw myself down and cried out, "Let my body, which had no pity upon yours, be crippled and let me be covered in boils!"
His students exclaimed, "Woe unto us to see you in such a state!" Rabbi Nahum replied, "Woe, indeed, but unto me if you did not see me in such a state!"
6. Gittin 61a
Our Rabbis taught, "Give sustenance to the poor of the non-Jews as well as the Jews. Visit the sick of the non-Jews as well as the Jews. Bury the dead of the non-Jews along with the dead of Israel. Do all these things because of the sake of peace."

7. Rabbi Israel Salanter
A person should be more concerned with spiritual matters than with material matters, but another person's material welfare is his own spiritual concern.